The present invention relates to a tool change device and a tool change method which selects one of two or more tools respectively held in two or more hold portions formed on a tool magazine and replaces a tool mounted on a main spindle with the thus selected tool.
In a tool change device of this type, when a tool held in the hold portion of a tool magazine exceeds a predetermined number of times of use or is damaged, the tool must be replaced with a new one. In this case, conventionally, an operator directly removes the old tool from the hold portion of the tool magazine and then mounts a new one onto the same hold portion of the tool magazine by hand. However, the tool magazine is generally disposed adjacent to a working position at which a main spindle is disposed and also the tool magazine is so arranged as to perform its operation such as rotation or the like in synchronization with a tool change operation. For this reason, in the conventional tool change device, while the working operation is stopped temporarily, the replacement of the old tool with a new one is carried out with respect to the hold portion of the tool magazine. That is, at first, the old tool is manually removed from the hold portion of the tool magazine and, afterwards, a new one is also manually inserted into the same hold portion of the tool magazine. However, it takes time to execute such manual tool replacement operation and, at the same time, the operator must be always present on the spot during the tool replacement operation, which results in a poor operation efficiency. This in turn lowers the working efficiency of the working operation.
Further, in a tool change device of the above-mentioned type, there is provided a tool magazine of a rotation type which is used to hold a plurality of tools on standby. And, as the need arises, a tool mounted on a main spindle is replaced with one of the tools held on the tool magazine by a tool change arm.
The above-mentioned conventional tool change device, for example, when replacing a tool which is damaged during the working operation, such replacement is normally carried out by means of the main spindle or tool magazine. When the tool replacement is executed by means of the main spindle, the operation of a machine must be stopped and a cover must be removed for the operation, which results in the waste of much time. When two or more tools are replaced, since the tools are taken out from the tool magazine, the above-mentioned operation must be executed repeatedly. Also, when changing the tools by means of the tool magazine, the tool magazine is indexingly rotated to thereby index a vacant hold portion to a tool replacing position, where an operator inserts a new tool. Or, an old tool held in the tool magazine is indexed to a tool replacing position, where the old tool is replaced with a new tool. After then, the tool magazine is indexingly rotated to thereby index a new tool to a take-out position for tool change, and the new tool is then taken out to the tool change position, before a tool change operation by the tool change arm can be carried out. Therefore, according to the prior art, not only does it take time to execute the tool change operation but also, in any of the above conventional tool change devices, since the tool change operation is carried out by means of the tool magazine, the tools must be changed in a state in which the operation of the machine is stopped, for example, by cutting off the power of the machine. That is, the machine cannot be operated during the tool changing operation, which provides an obstacle to an improvement in the efficiency of the working operation.
Also, conventionally, there is a tool change device structured such that there are provided a main tool magazine and a subordinate tool magazine and tools are delivered and received between the two tool magazines. However, in this type of tool change device as well, the tool change with respect to the main spindle is carried out by means of the main tool magazine. That is, in this tool change device as well, there is left the above-mentioned problem that the efficiency of the working operation cannot be improved.